The present invention relates to sheet material handling systems, and more particularly to devices for separating signatures during the collating and binding of, for example, books.
The binding and printing industries often rely on high-speed sheet material handling systems for printing, collating, and binding and otherwise handling sheet material, for example, sheets of paper. This sheet material, for example, individual sheets, newspapers, magazines, inserts and xe2x80x9consertsxe2x80x9d (that is, referring to sheet material used when collating newspapers), books, brochures, and the like, is typically, stacked in containers or xe2x80x9cmagazinesxe2x80x9d or xe2x80x9choppersxe2x80x9d and withdrawn from the magazines or hoppers for further processing. One particular sheet material that is handled in the binding and printing industry is what is known in the art as xe2x80x9csignaturesxe2x80x9d. Signatures are sheets of paper, that may have a spine fold, that contain at least two pages of text. Typically signatures contain 4 or more pages of text, for example, 30 or more pages of text. In the manufacture of books it is common to assemble the book on a collecting conveyor by sequentially withdrawing signatures from magazines, or hoppers, containing stacks of signatures. In producing a book, typically, a plurality of serially-arranged magazines, separating devices, and feeders are employed for gathering the printed sheets of, for example, signatures.
Typically, the separating devices separate and withdraw the sheet material from the magazines and feed the sheet material to a rotating drum. The rotating drum then feeds the sheet material to a conveyor which collects and transfers the separated printed sheets for collation, binding, or other operations. The separation of the sheet material from the stacked sheet material can be effected by a rotating disk separator aided by a suction device, known in the art as a xe2x80x9csuckerxe2x80x9d. One typical disk-type separator is disclosed in U.S. Pat. No. 6,193,229 B1, the disclosure of which is incorporated by reference herein in its entirety. The disk separator separates and feeds the sheet material to a rotating drum which accepts and retains the sheet material and conveys it to the conveyor. The disk separator, typically with the aid of the suction device, deflects the edge of the lower-most article of sheet material in the magazine stack. When the sheets to be withdrawn from the magazine are in the form of signatures, the deflected edge is typically the spine fold portion of the sheet. The rotating drum positioned below the disk separator typically includes some means of retaining the sheet material as it rotates, for example, devices known in the art as xe2x80x9cgrippersxe2x80x9d. The conveyor which receives the sheet material is typically a horizontal conveyor. This horizontal conveyor may also receive sheet material from other, typically serially-positioned, feeding drums. A common drive mechanism typically drives the separator, suction device, feed drum, and the conveyer.
The throughput of such systems is dependent upon on how closely together the sheet material is spaced, and on how fast the sheet material is moved. Accordingly, the throughput of such systems may be optimized by spacing the sheet material as closely together as possible and by maximizing the speed of operation of each of the components. For example, the rotational speed of the separator disk is of fundamental importance to performance of such sheet material handling systems. The faster the separator disk can rotate from the position where it enters the stack of sheet material to the position where the sheet material is separated, the better the system throughput.
Another important considering in the operation of disk-type separators is the alignment of the sheet material with separator disk. Since the disk separators of such devices rotate at high speed and typically xe2x80x9cbite intoxe2x80x9d the stack of sheet material in the magazine, misalignment of the sheet material and the disk can cause misfeeds, jamming, or even damage to the equipment. According to the prior art methods the disk separators rotate in one direction and thus repeatedly impact the stack of sheet material in essentially one direction. This repeated engagement of the disk with the stack can cause the stack or individual articles within the stack to migrate or move in the direction of rotation of the disk. This migration of the sheet material can result in the misalignment and its potential consequences mentioned above. This disadvantage of the prior art is overcome by one aspect of the present invention.
Commonly-assigned U.S. Pat. No. 6,193,229 B1 discloses a method and apparatus for improving the throughput of a sheet material feeding system having a disk-type separator. This improvement is provided by using a servo-motor-driven disk separator to vary the speed of rotation of the disk separator. The speed of the servo-motor is monitored and controlled by means of a servo-control system, that is, an automated feed-back control loop. Though the method and apparatus for feeding disclosed in U.S. Pat. No. 6,193,229 B1 provides an effective means for controlling and feeding sheet material, the present invention provides improvements which further enhance the effectiveness of disk-type sheet-material feeders.
The present invention provides methods and apparatus which address many of the limitations of prior art methods and apparatus. One aspect of the present invention is a feeder for delivering at least one article of sheet material to a conveyer. The feeder includes: a rotatable separator disk for separating stacked articles of sheet material; a servomotor mechanically coupled to the separator disk adapted to impart reciprocating rotation to the separator disk; and a rotatable feed drum oriented to receive the article separated by the separator disk and to transfer the article of sheet material to the conveyor. The articles of sheet material may be sheets of paper, signatures, newsprint, magazines, inserts, onserts, flyers, or brochures. It will be understood by those familiar with the art that the conveyor may be a collator or a gatherer. In one aspect of the invention, the servomotor reverses the rotation of the separator disk after the disk enters the stacked articles of sheet material. The feeder may further include a servo-control system coupled with the servomotor. The servomotor is typically adapted to rotate the disk in a first direction and rotate the disk in a second direction, opposite the first direction. The servo-control system is typically programmable.
One advantage of the present invention compared to the prior art is that the back and forth motion of the separator tends to prevent movement or migration of the sheet material in the magazine, which can characterize prior art systems having non-reciprocating motion of the disk. For example, the return stroke of the disk helps to compensate for any deflection of the stack of sheet material that occurs due to the separating stroke. Thus, according to one aspect of the present invention, misalignment of the sheet material with the separator disk or drum, which can cause misfeeds or otherwise interfere with proper operation of the feed system, is minimized or eliminated.
Another aspect of the present invention is a method for separating articles of sheet material. The method includes: providing a separator disk for separating at least one article of sheet material from a stack of sheet material; providing a servomotor for rotating the separator disk; and reciprocatingly rotating the separator disk to separate the articles of sheet material from the stack of sheet material. Reciprocatingly rotating is typically practiced by a) rotating the separator disk in a first direction and b) rotating the separator disk in a second direction, opposite the first direction. Steps a) and b) are typically repeated, for example, b) may be practiced immediately after a). Also, a) is typically practiced by accelerating the disk to first rotational speed and b) is practiced by accelerating the disk to second rotational speed; the first rotational speed may be about equal to the second rotational speed.
Another aspect of the present invention is a method for separating articles of sheet material and feeding the articles of sheet material to a conveyor. The method includes: providing a magazine containing at least one article of sheet material; providing a separator disk for separating at least one article of sheet material in the magazine; providing a feed drum oriented to receive the at least one separated article of sheet material and transfer the at least one separated article to the conveyor; reciprocatingly rotating the separator disk to separate the at least one article of sheet material from the magazine; transferring the at least one separated article of sheet material from the magazine to the feed drum; and transferring the separated at least one article of sheet material from the feed drum to the conveyor. This method may further include deflecting the edge of the article of sheet material prior to transferring the separated article from the magazine to the feed drum, for example, by applying a source of vacuum to the article of sheet material.
A still further aspect of the present invention is a system for separating articles of sheet material. The system includes: a rotatable separator disk for separating stacked articles of sheet material; a motor operatively connected to the separator disk for rotating the separator disk; and a programmable controller for controlling the operation of the motor. The programmable controller is typically programmed to operate the motor whereby the separator disk is reciprocatingly rotated, that is, the separator disk is rotated in a first direction and then rotated in a second direction, opposite the first direction, for example, immediately after rotating the disk in the first direction.
An even further aspect of the present invention is a feeder for delivering articles of sheet material to a conveyer. The feeder includes: a rotatable separator disk for separating stacked articles of sheet material; a motor operatively connected to the separator disk for rotating the separator disk; a programmable control system for controlling the operation of the motor; and a rotatable feed drum oriented to receive the articles of sheet material separated by the separator disk and transfer the articles of sheet material to the conveyor. The programmable control system is typically programmed to control at least the speed of rotation of the motor. In one aspect of the invention, the programmable control system is programmed to operate the motor whereby the separator disk is reciprocatingly rotated.
A still further aspect of the present invention is a method for separating articles of sheet material and feeding the articles of sheet material to a conveyor. The method includes: providing a magazine containing articles of sheet material; providing a separator disk driven by a motor for separating at least one article of sheet material in the magazine; providing a programmable controller system for controlling the rotation of the separator disk; providing a feed drum oriented to receive at least one separated article of sheet material and transfer the separated article of sheet material to the conveyor; rotating the separator disk in response to the programmable controller to separate at least one article of sheet material from the magazine; transferring the at least one separated article of sheet material from the magazine to the feed drum; and transferring the at least one separated article of sheet material from the feed drum to the conveyor. This method may further include deflecting an edge of the article of sheet material prior to transferring the separated article of sheet material from the magazine to the feed drum. Transferring the separated article of sheet material from the magazine to the feed drum is typically practiced by grasping the article with grippers mounted on the feed drum. Again, in one aspect of the invention, rotating the separator disk in response to the programmable controller is practiced by reciprocatingly rotating the separator disk. For example, in one aspect of the invention, reciprocatingly rotating the separator disk is practiced whereby misalignment of the articles of sheet material in the magazine is minimized.
These and other embodiments and aspects of the present invention will become more apparent upon review of the attached drawings, description below, and attached claims.